1. Field of the Invention
The present invention generally relates to surgical access devices and, more particularly, to an access seal providing passage of instrumentation and for maintaining pneumoperitoneum during laparoscopic surgeries.
2. Description of Related Art
Surgical access devices, such as a trocar 10 illustrated in FIG. 1, typically include a cannula 2 and a valve housing 4 that define a working channel 6 across a body wall 7, such as an abdominal wall, and into a body cavity 8, such as an abdominal cavity. The cannula is typically formed as an elongate rigid cylinder that is inserted, with the help of an obturator, into the body cavity to provide access across the body wall.
In a typical abdominal laparoscopic surgery, the abdomen is insufflated to pressurize and thereby enlarge the cavity within which a surgical procedure is to be performed. Various instruments used in the procedure are inserted, previously one at a time, through the working channel of the trocar to perform the surgery. In order to maintain the insufflation pressure when the instrument is inserted through the trocar, a valve has been provided in the housing to form a seal around the instrument. These instrument valves have typically been provided in the form of septum valves. When the instrument is removed, a zero-closure valve has typically been provided to seal the trocar in order to maintain the insufflation pressure. A zero-closure valve such as a double duckbill valve disclosed in U.S. Pat. No. 6,162,196, which is incorporated herein by reference, may be used.
Surgical instruments, however, vary in size and diameter. While the zero-closure valves can accommodate a relatively wide range of diameters, the septum valves are generally capable of stretching only a nominal amount to accommodate larger diameters. Specifically, the septum valves are generally formed in valve sets that are limited to the range of instruments that they can accommodate. When an instrument was required that had a diameter outside the range of a valve set, the entire trocar or at least the housing supporting the valve set had to be replaced with one that could accommodate the new instrument. In some cases, septum valves having universal seals were provided to accommodate different ranges of instrument diameters. These universal seals were typically made of elastic and tearable materials that often tear or puncture causing loss of insufflation gases. Attempts have also been made to include multiple septum seals to accommodate instruments having various diameters. For example, a septum valve may include one septum seal to engage large diameter instruments and another septum seal to engage smaller diameter instruments. These septum valves with multiple septum seals are typically more expensive to manufacture. Moreover, the seals are still limited to the specific range of instruments they can support.
Accordingly, there is a need in the art for a universal access seal capable of accommodating a wide range of instrument sizes. In particular, the universal access seal should be able to sealingly engage instruments of various diameters ranging from about 3.5 mm to about 12.9 mm. An access seal covering this range of instruments would reduce adjustments and, thus, time and costs required during surgery. It is also desirable for the universal access seal to perform when a sharp instrument is inserted off-center or when an instrument is moved radially after insertion. It is further desirable that the universal access seal facilitates the insertion and removal of instruments including tissue removal.